Collapsible bit



March 6, 1934- c. E. BANNISTER COLLAPSIBLE BIT Filed sept. 14, 1951 www Patented Mar. 6, 1934 UNITED STATES PATENT OFFICE My present invention relates to bits, and more particularly to a novel and improved bit primarily designed for use in the drilling of deep bores, such as oil wells.

In the drilling of deep oil wells, many advantages are to be obtained by casing the well as the drill descends therein. A diftlculty encountered during such practice, however, resides in the withdrawal of the bit through the casing, which is of necessity of a lesser internal diameter than the diameter of the bore being formed.

An important object of the present invention, therefore, resides in the provision of a bit having a plurality of cutting blades mounted for rocking on said bit in such a manner as to permit the bit and blades to be withdrawn through the casing which has followed the bit in its descent.

Another important feature of the present invention resides in the provision of resilient means to normally retain said cutting blades in cutting position, said blades being rocked and collapsed, against the tension of said resilient means, when, during withdrawal, said blades encounter the aforementioned casing.

Another object of the invention resides in pivoting said blades off center, so that a greater amount of rock will be possible.

'I'he advantages and benefits of a bit equipped with my novel collapsible cutting blades will be instantly apparent to and appreciated by those skilled in this art.

Other features and objects of the present invention reside in the particular construction and arrangement of the parts of my novel blt, and all of the above, together with other objects and features of the invention, details of construction, combinations of parts, and advantages, will be hereinafter more fully pointed out, described and claimed.

Referring to the drawing, illustrating a preferred embodiment of the present invention,

Fig. 1 is a sectional elevation of my novel bit in the process of boring a well;

Fig. 2 is a bottom plan view of said bit; and

Fig; 3 is a side elevation thereof.

Referring now to the drawing, for a particular description of the invention, its construction and operation, 1 designates a bit` united to the lower end of a ldrill stem or string `2, by threading or in any other desired manner. Said bit 1 is provided with a plurality of radially projecting bosses 3, 'each boss being provided with a horizontal recess 4 within which is seated a cutting blade 5. Said cutting blades are mounted on pivot pins 6, the ends of said pins being headed over in recesses '7, as clearly illustrated.

It will be noted, from an inspection ofthe drawing, that the pins 6 are set off center of the blades 5, and that the normal tendency of the blades 5 would be to drop to the position illustrated at 8, in dotted lines, in Fig. 1, the bit 1 being provided with inclined recesses 9 communicating with the recesses 4 to permit such rocking of the blades 5. However, to offset this tendency on the part of the blades 5, the bit 1 is provided with a central recess 10 terminating at one end in a shoulder 11. A coiled spring l2 is housed within said recess 10, bearing at one end against the shoulder 11 and at its other 10 end against the upper edge of each of the blades 5.

Thus the spring 12 bearing down upon the upper inner ends of the blades 5. will maintain said blades in the position shown in full.lines in Fig. 1, and this normal position of thevblades 5 will be maintained during the formation of the bore 13. As the bit descendsl in the bore, it may be followed by the casing, indicated generally at 14, the bore of said casing being of so necessity of less diameter than the bore 13. When it is desired to withdraw the bit 1, for any purpose, it is withdrawn vertically through the bore 13 and casing 14. As the blades 5 engage with the lower surface. of the casing 14, they will be rocked on their pins 6 and deflected to the-position illustrated in Fig. 1, in dotted lines, or beyond, depending upon the inner diameter of the casing 14. This rocking of the blades 5 will be against the tension of the spring 12, as 9() will be readily understood,` and upon release of the pressure upon the outer ends of 'the blades, said spring 12 will automatically return said blades to normal position.

It will be understood and appreciated that any type of cutting blade desired may be utilized, those illustrated herein being for illustrative purposes only.

Thus, by the use of my novel bit, the operators are enabled to case the well as the drilling there- 10 of progresses, so that on withdrawalof the drill string and bit, after completion of the bore, the well is already cased, thus resulting in a considerable saving in time and expense.

While I have necessarily described my present invention somewhat in detail, it will be appreciated that I may vary the size, shape and arrangement of parts within reasonably wide limits, Without departing from the spirit of the invention. llo

My invention is further described and defined in the form of claims as follows:

1. A bit of the kind described, comprising a body portion having a central recess therein, a plurality of radial bosses thereon, each of said bosses being provided with an outer horizontal recess at its bottom and with an inclined recess interposed between said central recess and said horizontal recesses, a cutting blade pivotally mounted in each of said sets of recesses, and a common resilient means in said central recess bearing against each of said blades to normally hold said blades in radial cutting position, said blades being collapsible against the tension of said resilient means, when pressure is exerted on their outer upper ends, to within the periphery of said bosses, the pivot point of each of said blades being off center thereof and located in substantial register with said interposed inclined recess to permit said collapsing of said blades.

2. A bit of the kind described, comprising a body portion having a central recess therein, a plurality of bosses projecting radially therefrom, each of said bosses being provided with an outer horizontal recess and with an inclined recess interposed between said central recess and said horizontal recesses. and in communication therewith, a cuttingblade pivotally mounted in each of said sets of recesses in each boss and projecting into the central recess in said bit, and a spring housed within the recess iny said bit andconstantly exerting pressure against the upper inner ends of each of said cutting blades to normally maintain said blades in radial cutting position.

CLYDE E. BANNISTER. 

